Dell 6000: Upgraded RAM,laptop wont switch ON

Hello,

I have a Dell Inspiron 6000, which currently has 2 256MB DDR RAM. I changed one of those for a

1GB DDR2 667MHz SODIMM PC2 5300 now the laptop will not switch on. I have tried changing the RAM back round still no joy.

Is this RAM compatible??

What could possibly be wrong???

Many Thanks in Advance,

J.J.